Park-lock mechanisms already exist in many different forms in the prior art. These mechanisms commonly include a toothed gear mounted on the transmission shaft, or a like shaft, and they include a latch or lever which can be manually positioned into and out of engagement with the toothed gear, all for the purpose of restraining rotation of the transmission members and thereby securing the vehicle in a non-mobile position so that it cannot move. These park-lock mechanisms are commonly employed in present-day automobiles, trucks, tractors and other vehicles. The operator simply positions the transmission shift lever to a park position, and the mechanism then locks and restrains the transmission against movement. Examples of some prior art locking mechanisms and arrangements are shown in U.S. Pat. Nos. 2,689,029 and 2,727,603 and 2,875,856 and 2,881,872 and 3,346,081. Generally speaking, the aforesaid prior art patents show arrangements and mechanisms for moving a latch or lever into and out of engagement with a toothed gear on a shaft, such as a transmission shaft, for restraining the movement of a vehicle.
However, the prior art arrangements are complicated and not fully-reliable and sturdy and they commonly require that the locking latch or lever be arranged so that it can immediately seat and lock with the toothed gear at the time that the operator is maneuvering the shift lever. Accordingly, it is a general object of this invention to improve upon the prior art mechanisms and arrangements, such that the present invention provides a sturdy, reliable, and automatically-engaging type of park-lock mechanism for vehicles.
That is, the present invention provides a park-lock mechanism wherein the operator can set the shift lever to a park position and the mechanism will automatically operate to move a lever or latch to a restraining position with a toothed gear at the initial moment that the vehicle attempts to move and the toothed gear rotates a very slight amount.
Still further, it is an object of this invention to provide a park-lock mechanism wherein the locking latch or lever is under the control of a single type of control member, including a lever, which thereby only requires that the locking latch or lever be maneuvered through a small angle but with the result that the locking latch or lever is placed in a secure position either away from the toothed gear or into securing and engaged position with the toothed gear, all under the control of a single control lever. In accomplishing this objective, the present invention does not require that there be one mechanism for moving the locking latch or lever into the securing position and that there be another mechanism or element for maneuvering the locking latch or lever out of the securing position and free of the gear tooth. Thus, the present invention provides a simplified but reliable and sturdy park-lock mechanism.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.